Currents of the Indian Ocean
The pattern of circulation of currents in the Indian Ocean differs from the general pattern of circulation in the Atlantic Ocean and the Pacific Ocean.
This is because Indian Ocean is blocked by the continental masses in the north.
The general pattern of circulation in the southern section of the Indian Ocean is anti clockwise as that of other oceans.
But in the northern section there is a clear reversal of currents in winter and summer.
These are completely under the influence of the seasonal changes of the monsoon winds.
So there is a clear reversal of currents in the winter and summer season i.e. southwestwards during the north-east Monsoon, north-eastwards during the southwest Monsoon and variable during transition season.
During winters Srilanka divides the currents of the Arahian Sea from those of the Bay of Bengal.
The North Equatorial Current flows westward just south of Srilanka with distinct counter equatorial current flows between it and the South Equatorial Current.
At this time in the northern section, the whole of Bay of Bengal and Arabian Sea is under the influence of North East Monsoon.
The North East Monsoon drives the water of Bay of Bengal and Arabian Sea west wards to circulate in an anti clockwise direction.
This current is known as North East Monsoon Drift.
In summers, the northern section comes under the influences of South West Monsoon.
There is an easterly movement of water in the Bay of Bengal and Arabian Sea and produces a clockwise circulation.
This current is known as South West Monsoon Drift.
In general the summer’s currents are more regular than those of winter.
In the southern Indian Ocean, the South Equatorial Current flows from east to west.
It turns south-wards along the Coast of Mozambique in Africa.
A part of this current which flows between the mainland and the Madagascar Island is known as warm Mozambique Current.
After the confluence of these two currents, it is called Aghulas Current.
It then turns eastwards and merges with the West Wind Drift.
The West Wind Drift flows across the ocean in west east direction in the higher latitudes to reach the southern tip of Australia.
A branch of this stream turns north to flow along the western coast of Australia as cold West Australian Current.
West Australian Current later joins the South Equatorial Current to complete the circuit.